The present invention relates to a novel herbicidal synergistic composition that contains a combination of herbicides suitable for selectively controlling weeds in crops of cultivated plants, typically in crops of maize. The invention further relates to a process for controlling weeds in crops of cultivated plants and to the use of said novel composition for this purpose.

wherein either A1 is nitro and A2 is hydrogen or A1 is methyl and A2 is methoxy, and their salts, possess herbicidal activity, as is described for example in EP-A-0 338 992.
It has now surprisingly been shown that a combination of active compounds, in a ratio varying within specific limits, i.e. an active ingredient of formula I with one or more of the herbicides of formulae 2.1 to 2.33 listed below, which are known and are partly available commercially, exerts a synergistic effect that is able to control the majority of weeds occurring preferably in crops of cultivated plants preemergence as well as postemergence.
Accordingly, the present invention provides a novel synergistic composition for the selective control of weeds that, in addition to customary inert formulation assistants, contains as active ingredient a mixture of
a) a compound of formula I 
xe2x80x83wherein either A1 is nitro and A2 is hydrogen or A1 is methyl and A2 is methoxy, as well as their salts, and
b) a synergistically active amount of one or more compounds selected from the compound of formula 2.1 
xe2x80x83wherein
R1 is CH2xe2x80x94OMe, ethyl or hydrogen,
R2 is hydrogen or R1 and R2 together are the group xe2x80x94CHxe2x95x90CHxe2x80x94CHxe2x95x90CHxe2x80x94;
xe2x80x83and the compound of formula 2.2 
xe2x80x83and the compound of formula 2.3 
wherein R6 is CH(Me)xe2x80x94CH2OMe or  less than S greater than CH(Me)xe2x80x94CH2OMe;
xe2x80x83and the compound of formula 2.4 
wherein R7 is chlorine or SMe, R8 is ethyl and R9 is ethyl, isopropyl or tert.-butyl;
xe2x80x83and the compound of formula 2.5 
wherein R10 is ethyl or n-propyl, R11 is COOxe2x88x92 1/2 Ca++, xe2x80x94CH2xe2x80x94CH(Me)Sxe2x80x94CH2CH3 or the group
xe2x80x83and X is oxygen, Nxe2x80x94Oxe2x80x94CH2CH3 or Nxe2x80x94Oxe2x80x94CH2CHxe2x95x90CHxe2x80x94Cl; and the compound of formula 2.6 
wherein R12 is hydrogen, methoxy or ethoxy, R13 is Me, methoxy or fluorine, R14 is COOMe, fluorine or chlorine, R15 is hydrogen or Me, Y is methane or nitrogen, Z is methane or nitrogen and R16 is fluorine or chlorine;
xe2x80x83and the compound of formula 2.7 
wherein R17 is hydrogen or xe2x80x94C(O)xe2x80x94S-n-octyl;
xe2x80x83and the compound of formula 2.8 
wherein R18 is bromine or iodine;
xe2x80x83and the compound of formula 2.9 
wherein R19 is chlorine or nitro;
xe2x80x83and the compound of formula 2.10 
wherein R20 is fluorine or chlorine and R21 is xe2x80x94CH2xe2x80x94CH(Cl)xe2x80x94COOCH2CH3 or xe2x80x94NHxe2x80x94SO2Me;
xe2x80x83and the compound of formula 2.11 
wherein R22 is trifluoromethyl or chlorine;
xe2x80x83and the compound of formula 2.12
wherein R23 is NH2 or  less than S greater than NH2;
xe2x80x83and the compound of formula 2.13 
wherein Y1 is nitrogen, methine or Nxe2x80x94Me, Y2 is nitrogen, methine or Cxe2x80x94I, Y3 is methine, Y4 is methine, or Y3 and Y4 together are sulphur or Cxe2x80x94Cl, Y5 is nitrogen or methine, Y6 is methyl or methoxy and R24 is CONMe2, COOMe, CH2xe2x80x94CH2CF3 or SO2CH2CH3, or the sodium salts thereof;
xe2x80x83and the compound of formula 2.14 
xe2x80x83and the compound of formula 2.15 
xe2x80x83and the compound of formula 2.16 
xe2x80x83and the compound of formula 2.17 
xe2x80x83and the compound of formula 2.18 
xe2x80x83and the compound of formula 2.19 
xe2x80x83and the compound of formula 2.20 
xe2x80x83and the compound of formula 2.21 
xe2x80x83and the compound of formula 2.22 
xe2x80x83and the compound of formula 2.23 
xe2x80x83and the compound of formula 2.24 
xe2x80x83and the compound of formula 2.25 
xe2x80x83and the compound of formula 2.26 
xe2x80x83and the compound of formula 2.27 
xe2x80x83and the compound of formula 2.28 
xe2x80x83and the compound of formula 2.29 
xe2x80x83and the compound of formula 2.30 
xe2x80x83and the compound of formula 2.31 
xe2x80x83and the compound of formula 2.32 
xe2x80x83and the compound of formula 2.33 
In the above formulae, xe2x80x9cMexe2x80x9d signifies the methyl group. The invention also embraces the salts that the compounds of formula I are able to form with amines, alkali metal bases and alkaline earth metal bases or quarternary ammonium bases. Salt-forming alkali metal and alkaline earth metal hydroxides include the hydroxides of lithium, sodium, potassium, magnesium or calcium, those of sodium or potassium being especially preferred.
Illustrative examples of amines suitable for forming ammonium salts are ammonia, as well as primary, secondary, and tertiary C1-C18alkylamines, C1-C4hydroxyalkylamines and C2-C4alkoxyalkylamines, typically methylamine, ethylamine, n-propylamine, isopropylamine, the four isomeric butylamines, n-amylamine, isoamylamine, hexylamine, heptylamine, octylamine, nonylamine, decylamine, pentadecylamine, hexadecylamine, heptadecylamine, octadecylamine, methyl ethylamine, methyl isopropylamine, methyl hexylamine, methyl nonylamine, methyl pentadecylamine, methyl octadecylamine, ethyl butylamine, ethyl heptylamine, ethyl octylamine, hexyl heptylamine, hexyl octylamine, dimethylamine, diethylamine, di-n-propylamine, diisopropylamine, di-n-butylamine, di-n-amylamine, diisoamylamine, dihexylamine, diheptylamine, dioctylamine, ethanolamine, n-propanolamine, isopropanolamine, N,N-diethanolamine, N-ethylpropanolamine, N-butylethanolamine, allylamine, n-butenyl-2-amine, n-pentenyl-2-amine, 2,3-dimethylbutenyl-2-amine, dibutenyl-2-amine, n-hexenyl-2-amine, propylenediamine, trimethylamine, triethylamine, tri-n-propylamine, triisopropylamine, tri-nbutylamine, triisobutylamine, tri-sec-butylamine, tri-n-amylamine, methoxyethylamine and,ethoxyethylamine; heterocyclic amines such as pyridine, quinoline, isoquinoline, morpholine, piperidine, pyrrolidine, indoline, quinuclidine and azepine; primary arylamines such as anilines, methoxyanilines, ethoxyanilines, o-, m- and p-toluidines, phenylenediamines, benzidines, naphthylamines and o-, m- and p-chloroanilines. Preferred amines are triethylamine, isopropylamine and diisopropylamine. The compound of formula I, wherein A1 is methyl and A2 is methoxy, is most preferably present in the form of the diisopropylammonium salt.
It is entirely surprising that the combination of the compound of formula I with one or more herbicides selected from formulae 2.1 to 2.33 exceeds the expected additive action against the weeds to be controlled and thus in particular enhances the activity range of the individual components in two respects: On the one hand, the concentrations of the single compounds of formulae I and 2.1 to 2.33 are reduced whilst retaining good activity. On the other hand, the novel herbicidal combination also achieves a high degree of weed control where the single compounds have become no, longer agriculturally effective at low concentrations. The consequence is a substantial broadening of the activity spectrum against weeds and an additional increase in the selectivity for the cultivated plants that is necessary and desirable in the event of unintentional overapplication of herbicide. In addition, the novel composition permits greater flexibility with respect to subsequent crops while retaining the excellent control of weeds in crops of cultivated plants.
The composition of the invention may be used against a large number of agronomically important weeds, typically Stellaria, Nasturtium, Agrostis, Digitaria, Avena, Setaria, Sinapis, Lolium, Solanum, Phaseolus, Echinochloa, Scirpus, Monochoria, Sagittaria, Bromus, Alopecurus, Sorghum halepense, Rottboellia, Cyperus, Abutilon, Sida, Xanthium, Amaranthus, Chenopodium, Ipomoea, Chrysanthemum, Galium, Viola, and Veronica. The composition of this invention is suitable for all methods of application commonly used in agriculture, including preemergence application, postemergence application and seed dressing. The composition of the invention is preferably suitable for weed control in crops of cultivated plants, typically cereals, rape, sugar beet, sugar cane, plantations, rice, maize and soybeans and for the non-selective control of weeds.
Crops will also be understood as meaning those crops that have been made tolerant to herbicides or classes of herbicides by conventional breeding or genetic engineering methods.
The compounds of formulae 2.1 and 2.3 to 2.13 are known under the names imazamox, imazethapyr, imazaquin, imazapyr, dimethenamid, atrazine, terbutylazin, simazine, terbutyrn, prohexadione calcium, sethoxydim, clethodim, tepraloxydim, flumetsulam, metosulam, pyridate, bromoxynil, ioxynil, sulcotrione, carfentrazone, sulfentrazone, isoxaflutole, glufosinate, primisulfuron, prosulfuron, rimsulfuron, halosulfuron, nicosulfuron, and thifensulfuron and are described in the Pesticide Manual, eleventh ed., British Crop Protection Council, 1997 under the entry numbers 412, 415, 414, 413, 240, 34, 692, 651, 693, 595, 648, 146, 49, 339, 495, 626, 88, 425, 664, 112, 665, 436, 382, 589, 613, 644, 389, 519 and 704 The compound of formula 2.13, wherein Y1, Y3 and Y4 are methine, Y2 is Cxe2x80x94I, R24 is COOMe, Y5 is nitrogen and Y6 is methyl, is known under the name iodosulfuron (especially the sodium salt) from AGROW No. 296, Jan. 16th 1998, page 22. The S-enantiomer of the compound of forrmula 2.12 is registered under CAS reg. no. [35597-44-5]. The compound of formula 2.2, aRS,1xe2x80x2S(xe2x88x92)N-(1xe2x80x2-methyl-2xe2x80x2-methoxyethyl)-N-chloroacetyl-2-ethyl-6-methylaniline, as well as a compound of the general formula 2.3, (1S,aRS)-2-chloro-N-(2,4-dimethyl-3-thienyl)-N-(2-methoxy-1-methylethyl)-acetamide, are described for example in WO 97/34485. The compound of formula 2.9, wherein R19 is NO2, is known under the name mesotrione and is described for example in U.S. Pat. No. 5,006,158. The compound of formula 2.6, wherein R12 is ethoxy, R13 is fluorine, Y is methine, R14 is methoxycarbonyl, R15 is hydrogen and R16 is chlorine, is known under the name cloransulam, for example from AGROW no. 261, Aug. 2nd 1996, page 21.
In addition, the following compounds of the composition according to the invention are described in the Pesticide Manual, eleventh ed., British Crop Protection Council, 1997:
The compound of formula 2.7, wherein R17 is hydrogen, and the preparation thereof, are described in U.S. Pat. No. 3,790,571, the compound of formula 2.6, wherein R12 is ethoxy, Z is nitrogen, R13 is fluorine, R14 is chlorine and R15 is hydrogen and R16 is chlorine, is described in U.S. Pat. No. 5,498,773.
The compound of formula 2.21 and the preparation thereof are described in U.S. Pat. No. 5,183,492, the compound of formula 2.22 is described under the name isoxachlortole in AGROW no. 296, Jan. 16th 1998, page 22. The compound of formula 2.31 is described under the name fentrazamide in The 1997 British Crop Protection Conferencexe2x80x94Weeds, Conference Proceedings Vol. 1, 2-8, pages 67 to 72, the compound of formula 2.32 is described under the name JV 485 (Isoxapropazol) in The 1997 British Crop Protection Conferencexe2x80x94Weeds, Conference Proceedings Vol. 1, 3A-2, pages 93 to 98.
Preferred synergistic mixtures according to the invention contain as active ingredients a compound of formula I and either the compound of formula 2.2 
(2.2,aRS,1xe2x80x2S(xe2x88x92)N-(1xe2x80x2-methy-2xe2x80x2methoxyethyl)-N-chloroacetyl-2-ethyl-6-methylaniline), or a compound of formula 2.3, or a compound of formula 2.4, wherein R7 is chlorine, R8 is ethyl and R9 is isopropyl, or R7 is chlorine, R8 is ethyl and R9 is tert.-butyl, or a compound of formula 2.6, wherein R12 is hydrogen, Z is methine, R13 is methyl, Y is nitrogen, R14 is fluorine, R15 is hydrogen and R16 is fluorine, or R12 is methoxy, Z is methine, R13 is methoxy, Y is methine, R14 is chlorine, R15 is methyl and R16 is chlorine, or a compound of formula 2.7, wherein R17 is xe2x80x94C(O)xe2x80x94S-n-octyl, or a compound of formula 2.9, or a compound of formula 2.11, wherein R22 is trifluoromethyl, or a compound of formula 2.12, or a compound of formula 2.13, wherein Y1 is nitrogen, Y2, Y3 and Y4 are methine, R24 is dimethylaminocarbonyl and Y5 is methine, or Y1, Y2, Y3 and Y4 are methine, R24 is methoxycarbonyl and Y5 is methine, or Y1, Y2, Y3 and Y4 are methine, R24 is 3-trifluoropropyl and Y5 is nitrogen, or Y1 is nitrogen, Y2, Y3 and Y4 are methine, R24 is ethylsulphonyl and Y5 is methine, or Y1 is Nxe2x80x94Me, Y2 is nitrogen, Y3 and Y4 together are Cxe2x80x94Cl, R24 is methoxycarbonyl and Y5 is methine, or a compound of formula 2.16, or a compound of formula 2.18, or a compound of formula 2.19, or a compound of formula 2.30.
A further group of preferred synergistic mixtures according to the invention contains as active ingredients a compound of formula I, the compound of formula 2.2 
(2.2,aRS,1xe2x80x2S(xe2x88x92)N-(1xe2x80x2-methyl-2xe2x80x2-methoxyethyl)-N-chloroacetyl-2-ethyl-6-methylaniline), as well as a compound selected from formula 2.4, wherein R7 is chlorine, R8 is ethyl and R9 is isopropyl, or R7 is chlorine, R8 is ethyl and R9 is tert.-butyl, and of formula 2.6, wherein R12 is hydrogen, Z is methine, R13 is methyl, Y is nitrogen, R14 is fluorine, R15 is hydrogen and R16 is fluorine, or R12 is methoxy, Z is methine, R13 is methoxy, Y is methine, R14 is chlorine, R15 is methyl and R16 is chlorine, and of formula 2.7, wherein R17 is xe2x80x94C(O)xe2x80x94S-n-octyl, and of formula 2.13, wherein Y1 is nitrogen, Y2, Y3 and Y4 are methine, R24 is dimethylaminocarbonyl and Y5 is methine, or Y1, Y2, Y3 and Y4 are methine, R24 is methoxycarbonyl and Y5 is methine, or Y1, Y2, Y3 and Y4 are methine, R24 is 3-trifluoropropyl and Y5 is nitrogen, or Y1 is nitrogen, Y2, Y3 and Y4 are methine, R24 is ethylsulphony and Y5 is methine, or Y1 is Nxe2x80x94Me, Y2 is nitrogen, Y3 and Y4 together are Cxe2x80x94Cl, R24 is methoxycarbonyl and Y5 is methine, and of formula 2.9, and of formula 2.11, wherein R22 is trifluorometkyl, and of formula 2.12, and of formula 2.16, and of formula 2.18, and of formula 2.19.
It has been found that particularly effective herbicidal combinations are the combinations of compounds of formula I with the compound of formula 2.2 
(2.2.,aRS,1xe2x80x2S(xe2x88x92)N-(1xe2x80x2-methyl-2xe2x80x2-methoxyethyl)-N-chloroacetyl-2-ethyl-6-methylaniline).
The composition according to the invention contains the active ingredient of formula I and the active ingredients of formulae 2.1 to 2.33 in any ratio, normally with an excess of one component over the others. In general, the mixture ratios (weight ratios) between the active ingredient of formula I and the components of formulae 2.1 to 2.33 lie between 1:2000 and 2000:1, especially between 200:1 and 1:200.
The rate of application can vary over a wide range and will depend on the nature of the soil, the type of application (pre- or postemergence), seed dressing, application to the seed furrow; no tillage application etc.), the cultivated plant, the weed to be controlled, the respective prevailing climatic conditions; and on other factors governed by,the type and time of application and the target crop. In general, the mixture according to the invention may be used at a rate of aplication of 1 to 5000 g of mixture/ha.
The mixtures of the compounds of formula I with the compounds of formulae 2.1 to 2.33 may be used in unmodified form, i.e. as obtained in the synthesis. Preferably, however, they are processed in conventional manner e.g. to emulsifiable concentrates, directly sprayable or dilutable solutions, dilute emulsions, wettable powders, soluble powders, dusts, granulates or microcapsules using the auxiliary agents customarily employed in formulation technology. As with the type of, compositions, the methods of applicationxe2x80x94such as spraying, atomising, dusting, wetting, scattering, or pouringxe2x80x94are selected in accordance with the intended objectives and the prevailing circumstances.
The formulations, i.e. the agents, preparations, or compositions containing the compounds of formula I and 2.1 to 2.33, and optionally one or more than one liquid or solid formulation assistant, are prepared in known manner, e.g. by homogeneously mixing and/or grinding the herbicide with said formulation auxiliaries, typically solvents or solid carriers. Surface-active compounds (surfactants) may additionally be used for preparing the formulations.
Examples of solvents and solid carriers are described in WO 97/34485, page 6.
Depending on the herbicide of formula I to be formulated, suitable surface-active compounds are nonionic, cationic and/or anionic surfactants and surfactant mixtures having good emulsifying, dispersing and wetting properties.
Examples of suitable anionic, non-ionic, and cationic surfactants are listed in WO 97/34485 on pages 7 and 8.
Also the surfactants customarily for the art of formulation and described, inter alia, in xe2x80x9cMc Cutcheon""s Detergents and Emulsifiers Annualxe2x80x9d MC Publishing Corp., Ridgewood N.J., 1981, Stache, H., xe2x80x9cTensid-Taschenbuchxe2x80x9d (Handbook of Surfactants), Carl Hanser Verlag, Munich/Vienna, 1981, and M. and J. Ash, xe2x80x9cEncyclopedia of Surfactantsxe2x80x9d, Vol I-III, Chemical Publishing Co., New York, 1980-81 are suitable for manufacture of the herbicides according to the invention.
The herbicidal compositions will usually contain from 0.1 to 99% by weight, preferably from 0.1 to 95% by weight, of compound mixture of the compound of formula I and the compounds of formulae 2.1 to 2.33, from 1 to 99.9% by weight of a solid or liquid formulation assistant, and from 0 to 25% by weight, preferably from 0.1 to 25% by weight, of a surfactant.
Whereas it is customarily preferred to formulate commercial products as concentrates, the end user will normally use dilute formulations. The compositions may also contain further ingredients, such as: stabilisers, e.g., where appropriate epoxidised vegetable oils (epoxidised coconut oil, rapeseed oil, or soybean oil); antifoams, typically silicone oil; preservatives; viscosity regulators; binders; and tackifiers; as well as fertilisers or other chemical agents. Particularly preferred formulations are made up as follows: (%=percent by weight)
Emulsifiable Concentrates:
Compound mixture: 1 to 90%, preferably 5 to 20%
Surfactant: 1 to 30%, preferably 10 to 20%
Liquid carrier: 5 to 94%, preferably 70 to 85%
Dusts:
Compound mixture: 0.1 to 10%, preferably 0.1 to 5%
Solid carrier: 99.9 to 90%, preferably 99.9 to 99%
Suspension Concentrates:
Compound mixture: 5 to 75%, preferably 10 to 50%
Water: 94 to 24%, preferably 88 to 30%
Surfactant: 1 to 40%, preferably 2 to 30%
Wettable Powders:
Compound mixture: 0.5 to 90%, preferably 1 to 80%
Surfactant: 0.5 to 20%, preferably 1 to 15%
Solid carrier: 5 to 95%, preferably 15 to 90%
Granulates:
Compound mixture: 0.1 to 30%, preferably 0.1 to 15%
Solid carrier: 99.5 to 70%, preferably 97 to 85%